Originally Posted by ajdelange
I'd use the one that says add about 2.5 grams of calcium chloride to 5 gal RO.
Taking this advice and preparing your mash and sparge water using RO water and the 0.5g CaCl2/1 gal ratio above, you'll roughly get the following concentrations:
Ca: 36 ppm
Mg: 0 ppm
Na: 0 ppm
Cl: 64 ppm
SO4: 0 ppm
You've got Nobel hops and the advice above was probably given with the basis that no sulfate is best for those hop flavor and the Ca is added in the form of CaCl2 for yeast health, Cl comes along with it. The Pilsen profile is very low Ca and the Yellow Malty profile has sulfate. Neither probably are better than what's listed above.
You'll want 4 oz of Weyermann 2% acidulated malt to get the room temperature pH to about 5.4 and can probably brew pretty confidently without checking pH because it's almost all base malt.
Carapils is a pale crystal malt but doesn't affect the pH much at the quantity you're using.